1. Field of the Invention
The present invention relates to a powdered or granular solid pesticide composition. More specifically, it relates to a powdered or granular solid pesticide composition, containing methyl isothiocyanate ("MITC" hereinbelow) as an effective component, capable of effectively controlling various plant parasitic nematodes and noxious soil fungi and insects which inhibit normal growth of plants by parasitic action in subterranean roots and tubers of plants in soil and capable of being readily applied to soil as a nematocide, a fungicide, and an insectcide with excellent applicability.
2. Description of the Prior Art
MITC represented by the chemical formula CH.sub.3 NCS is very volatile low melting point solid having a vapor pressure of 20.7 mmHg at 20.degree. C., a melting point of 35.degree. C., and a boiling point of 119.degree. C. It is commercially available as a nematocide, fungicide, and a said insecticide in the form of an oily preparation dissolved in an organic solvent. However, these MITC preparations have problems in that their application is troublesome since they must be injected into the soil at predetermined injection points through a special applicator and that the concentration distribution of the MITC is caused around each injection point and, therefore, uniform and effective pesticidal effects cannot be obtained and cultivated crops are susceptible to phytotoxity (or chemical damages).
Various attempts have been made to solve the above-mentioned problems. For example, powdered or granular pesticide compositions in which active components are supported on solid carriers have been conventionally used as a one preparation form of pesticide compositions for soil application. These solid type pesticide compositions have the advantage, as compared with the liquid type pesticide compositions, that uniform pesticide effects can be obtained and phytotoxity due to high local concentration of pesticides in soil does not easily occur since the solid type pesticide compositions can be readily and simply applied to soil and can also be readily mixed into soil without a special application therefor. However, the preparation of powdered or granular MITC compositions is difficult in practice for the following reasons:
(1) Since MITC is extremely volatile as mentioned above, it is very difficult to retain MITC stably on a solid carrier;
(2) Even if MITC can be supported on a solid carrier to some extent, the supported MITC tends to volatilize at once when a container containing the supported MITC is opened;
(3) Since the vapor of MITC is lachrymatory and skin irritative, volatilization of MITC during application is very noxious to an operator or worker; and
(4) When MITC is completely and densely solidified with a carrier, the above-mentioned volatilization and vaporization problems can be solved.
However, too dense solidification causes too slow releasing of MITC from the solidified MITC agents, which, in turn, causes phytotoxity due to the retention of MITC in soil for a long term and causes insufficient pesticide effects due to the too small releasing of MITC. Furthermore, the use of too expensive substances and complex preparation steps is not practical for pesticide compositions from an economical viewpoint.